Photoelectric device for ultra-violet radiation



Jan. 30, 1962 A. KROHS ETAL PHOTOELECTRIC DEVICE FOR ULTRA-VIOLET RADIATION Filed Nov. 27; 1956 In ven tors United States Patent 3,019,364 PHOTOELECTRIC DEVICE FOR ULTRA-VIOLET RADIATION Alfred Krohs and Fritz Schlohleiu, Jena, Germany, assignors to VEB Carl Zeiss Jena, Jena, Germany Filed Nov. 27, 1956, Ser. No. 624,705 Claims priority, application Germany Dec. 22, 1955 1 Claim. (Cl. 313-102) In the production of glass envelopes for photoelectric cells, image converters or the like for use with ultraviolet waves, a quartz window through which ultra-violet rays can pass must be sealed to a bulb of conventional soft glass. As is well known, the considerable difference between the heat expansion coeflicients of quartz and soft glass precludes a direct sealing there-between, for which reason such sealings are usually effected with the aid of intermediate glasses consisting of kinds of glass with different heat expansion coefficients so that there is only a relatively small difference between the heat expansion coefficients of the substances to be sealed.

To this end, it is known to melt tubular pieces of various intermediate glasses on to one another, the quartz window and the normal glass flask being sealed to the two ends of the connecting member thus produced. This known method results in an increase of the distance be tween the quartz window and the glass bulb which contains the light-sensitive element, but the associated increase in the distance which the light must travel from the entry window to the place where the light is to act, for insance, a photoemissive layer, is often undesirable.

To obviate this disadvantage, the invention proposes the production of a glass bulb with a melted-in quartz window on which intermediate glass rings of appropriate heat coefiicients are disposed around the outer edges of said quartz window and so sealed to said edges and to each other and to the wall of said bulb that said quartz window, said intermediate glass rings and that part of the wall of said bulb, which is to be sealed to the window lie in one common plane. The advantage of such an envelope is that the distance from the quartz window to the light-senstive layer is no longer than in the conventional construction of a corresponding photoelectric cell. Another advantage is that if the structure according to the invention is used, there is no need to have tubular material of different kinds of glass available. Another advantage is that where photoelectric cells or the like are provided with sockets, no modification is necessary as compared with the conventional construction without a 3,019,364 Patented Jan. 30, 1962 2 quartz window. This advantage is more particularly apparent in the case of secondary electron multipliers which are relatively complicated as regards construction and provision with sockets.

An example of how the invention can be applied is diagrammatically illustrated in the drawing in which FIG. 1 is a front view and FIG. 2 is a side view partially in section of a photoelectric cell according to the invention. In the drawing the reference 1 denotes a glass bulb forming part of an envelope containing a photo-emissive layer 2 and an anode 3. A quartz window 4 through which the ultra-violet rays can pass in the direction of the arrow is sealed to the bulb with the use of intermediate glass rings 5 to 7. The latter are made of glass in rod form with different heat expansion coetiicients, the glass used for the ring 5 having the smallest heat expansion coefiicient and the glass used for the ring 7 having the greatest heat expansion coefficient. To produce the union by fusion, the quartz window 4, rings 5 to 7 and the associated wall 8 of the glass bulb 1 are disposed in a single plane.

We claim:

A photoelectric device comprising at least a photoemissive layer sensitive to the ultra-violet range of radiation in an envelope consisting of a glass bulb with a quartz window, said photo-emissive layer lying in the path of said radiation entering through said window in said photoelectric device, said window being sealed to said bulb by means of a graded seal composed of several intermediate glass rings of appropriate heat coefiicients disposed around the outer edges of said quartz window and so sealed to said edges, to each other and to the wall of said bulb that said quartz window, said intermediate glass rings and the wall of said bulb which is to be sealed with the window lie in one common plane.

References Cited in the file of this patent UNITED STATES PATENTS 1,537,921 Mailey May 12, 1925 2,075,447 Smith Mar. 30, 1937 2,100,187 Handrek Nov. 23, 1937 2,144,519 Wilson Jan. 17, 1939 .2,232,322 Gilmore Feb. 18, 1941 2,237,065 Van Den Bosch Apr. 1, 1941 2,499,854 Ellefson Mar. 7, 1950 2,517,019 Nordberg Aug. 1, 1950 2,534,392 Walsh Dec. 19, 1950 2,549,504 Messana Apr. 17, 1951 

